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ABOVE
THE
WATER
LINE
By Sally Bethea
Sally Bethea is the
retired executive
director of Chat
tahoochee Riverkeeper
(chattahoochee. org),
a nonprofit environ
mental organization
whose mission is to
protect and restore the
drinking water supply
for nearly four million
people.
id you know that the Chattahoochee River, which flows
southwesterly through Atlanta, has one of the oldest and
most stable river channels in the United States? It has
been “locked in place” along the Brevard Fault Zone for
at least 185 million years.
By contrast, the Colorado River, which drains seven
states, is relatively young; geologists say that plateau
uplift, resulting in the river that we know today, took
place just five to six million years ago. There is some
evidence that tectonic activities which occurred
70 million years ago also contributed to the river’s
creation. Even assuming this earlier “birth,” the
Colorado is still a youngster, when compared to our
Chattahoochee.
I have always been fascinated by streams and rivers: where
they begin, how they formed and the type of landscape that
makes up their drainage basins, or watersheds. Not surprisingly, my
vacations often revolve around rivers.
In May, I traveled to southeastern Utah on a Sierra Club trip to
paddle the Colorado and Green Rivers and hike in several national
parks. The buttes, bluffs and mesas towering over these rivers proved
to be mesmerizing: massive, eroding rock shapes built of layer upon
layer of sandstone, limestone, volcanic rock, salt and shale over
millions of years. In this stone fantasyland, I envisioned the profile of
iconic desert writer Ed Abbey in one of the formations.
The ancestral Colorado River formed after the landscape uplifted
from an inland sea; water from the higher elevations then drained
to the northeast, the opposite direction of the flow of today’s river.
When the mountain range that fed the original Colorado was destroyed by faulting about 25
million years ago, the river reversed its course. New plateaus rose and the sediment-ladent’iver
“played the part of a stationary band saw”, cutting through two million year old rock to create
abysses like the Grand Canyon.
Closer to home, the Brevard Fault Zone, a prominent geologic feature of the southeastern
U.S., extends for nearly a thousand miles across the southern Appalachians. Its parallel ridges
are responsible for the Chattahoochee River’s northeast-to-southwest course through north
Georgia and its long, linear character.
Millions of years ago, there was more water in the Chattahoochee River system, until a
geological phenomenon called “stream capture” occurred. Eroding rivers battled each other
for ~ “ supremacy and ultimately the top of the Chattahoochee watershed
was cut off, its water diverted into the Savannah
River basin. Prior to this event, the ancestral
headwaters of the Chattahoochee extended
up into what is now North Carolina,
incorporating a much larger land
area and collecting more rainwater,
which increased the river volume
downstream.
The Tugaloo River, at the
top of the Savannah basin,
had eroded through a ridge
over thousands of years and
captured the Chattooga and Tallulah
Rivers, formerly tributaries to the
Chattahoochee. Their waters began to crash
dramatically over what is now Tallulah Falls, flowing to the Atlantic
Ocean instead of the Gulf of Mexico. Atlanta’s loss was Augusta’s and Savannah’s gain.
Today, the watershed upstream of Atlanta — about a thousand square miles — is one
of the smallest drainages in the country that supplies a major metropolitan area with river
water. When rain fails to fall over this small watershed for months, especially in the summer,
the water level in the Chattahoochee system begins to drop. Our water supply challenges in
Atlanta are largely a function of our geological history — and a decision made nearly 200 years
ago to locate our metropolis near the top of a river basin on the banks of a small river.
Our country is blessed with nearly three million miles of rivers. Each one of them has a
geologic story to tell with chapters that will continue to unfold through the millenia. QD
ECO BRIEFS
• Keep Atlanta Beautiful is moving one
• of its community recycling centers from
• Old Fourth Ward to Kirkwood beginning
• on Sept. 9. The new center will be located
l at Coan Middle School,
• 1550 Hosea L. Williams
• Drive. Electronics, metals,
• glass, latex paint, paper
. shredding, Styrofoam,
J textiles and books are all
• accepted at the monthly
• recycling events, which
? are held on the second
J Saturday of each month
• from 10 a.m. to 3 p.m.
• The last recycling day at
I Walden Middle School
• in the Old Fourth Ward
will be Aug. 12. For more details, visit
KeepAtlantaBeautiful.org.
Piedmont Park has replaced often-
photographed
Climbing Magnolia,
which toppled over last
summer after to rot.
Based on its rings, many
believe the magnolia
dates back to the Cotton
States Exhibition in
1895, which was held in
what is now the grounds
of the park. A 20’
magnolia, with a 70”
root ball, weighing over
8,000 pounds has been
successfully installed in Piedmont Park to
replace the Climbing Magnolia thanks to
$20,000 donation from the Vasser Woolley
Foundation.
Community
Foundation for Greater
Atlanta named Trees
Adanta as one of the
recipients of its 33rd
annual Managing for
Excellence Award. Trees
Atlanta and co-recipient
Literacy Atlanta will each
receive $75,000. The
nonprofit has planted
more than 119,000 trees since 1985,
helping to improve air quality and reduce
carbon emissions.
The Wylde Center will host the
second annual Mulberry Fields Gone
Wylde on Saturday, July 15, from 6 to
9 p.m. The festive outdoor evening will
feature live music by Webster, food and
drinks for purchase from Fox Brothers
and other vendors, children’s games and
much more. After sunset, the Chickabilly,
a metal sculpture/fire bowl will be set
ablaze. The event
is free for Wylde
Center members
and children 12
and under, and $10
for non-members.
Mulberry Fields is
located “down the
alley” at 1301 Iverson
St., in Candler Park.
Mulberry Fields
Gone Wylde will be
held rain or shine and is sponsored by the
Candler Park Neighborhood Organization,
Premier Grease, Small Business Services and
the Elarris Bathrick Basch family. Proceeds
will benefit Mulberry Fields. For more
information and to purchase tickets, visit
wyldecenter.org/mulberry-fields-gone-
wylde-2017. [El
22 July 2017 | na
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